High germanium doping of GaN films by ammonia molecular beam epitaxy
High germanium doping of GaN films by ammonia molecular beam epitaxy
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DOI：
10.1016/j.jcrysgro.2018.12.009
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发表时间：
2019-02-15
影响因子：
1.8
通讯作者：
Speck, James S.
中科院分区：
文献类型：
--
作者：
Fireman, Micha N.;L'Heureux, Guillaume;Speck, James S.
介绍了氨分子束外延生长氮化镓（GaN）并掺杂元素锗（Ge）的方法。生长研究改变了氮化镓生长速率、衬底生长温度和元素锗通量，揭示了几种掺杂关系。正如预期的那样，Ge掺入量随着通量的增加而增加，并且很容易实现类似于10(17)cm（-3）到10(20)cm（-3）的掺杂范围。观察到衬底温度对薄膜电性能有很强的依赖性，最佳生长温度为740℃，低于氨分子束外延的标准氮化镓生长条件。正如用其他技术观察到的那样，怀疑在较高的生长温度下存在补偿效应。从电学和光学测量来看，在最高掺杂浓度下，晶体学缺陷是明显的，然而，这种高掺杂薄膜的薄层对于器件中的接触层和隧道结非常感兴趣。
Gallium Nitride (GaN) grown by ammonia molecular beam epitaxy and doped with elemental Germanium (Ge) is presented. Growth studies varying the GaN growth rate, substrate growth temperature and the elemental Ge flux reveal several incorporation dependencies. Ge incorporation increases with flux, as expected, and a doping range from similar to 10(17)cm(-3) to 10(20)cm(-3) was readily achieved. A strong substrate temperature dependence on the electrical properties of films grown is observed, with an optimal growth temperature of 740 degrees C, lower than standard GaN growth conditions for ammonia molecular beam epitaxy. Compensation effects at higher growth temperatures are suspected, as observed with other techniques. Crystallographic defects are apparent at the highest doping concentrations from electrical and optical measurements, however thin layers of such highly doped films are of great interest for contact layers and tunnel junctions in devices.